1. Field of the Invention
The present invention relates generally to an electrical connector, and more particularly to an improvement in an electrical connector used for putting connecting terminals provided on a circuit board, such as a flexible printed circuit board (FPC), conductors provided in a flexible flat cable assembly (FFC) or the like in electrical connection with other electrical parts, such as a main solid circuit board.
2. Description of the Prior Art
In the field of electronic apparatus including various portable telephones, a relatively small-sized flexible printed circuit board or flexible flat cable assembly is often mounted on a main printed circuit board, on which various electrical parts are directly mounted, by means of an electrical connector which is fixed to and connected electrically with the main printed circuit board. The electrical connector has a plurality of conductive contacts for coming into contact with connecting terminals provided on the flexible printed circuit board or conductors in the flexible flat cable assembly and is operative to connect, through the conductive contacts, the connecting terminals provided with the flexible printed circuit board or the conductors in the flexible flat cable assembly with conducting circuit pattern portions formed on the main printed circuit board.
For example, a previously proposed electrical connector, which is used for mounting a flexible printed circuit board on a main printed circuit board, is provided with a housing made of insulator which has an opening through which the flexible printed circuit board is partially inserted into the housing. In the housing, a plurality of conductive contacts are arranged along the opening. These conductive contacts are operative to come into contact with a plurality of connecting terminals provided on the flexible printed circuit board when the flexible printed circuit board is partially inserted into the housing through the opening. The electrical connector is further provided with an actuator which is attached rotatably to the housing to be common to the conductive contacts arranged in the housing. When the actuator is rotated in regard to the housing, each of the conductive contacts is partially moved in the housing.
Each of the conductive contacts arranged in the housing is made of conductive resilient material to have a fixed portion which is fixed to the housing and a movable portion coupled with the fixed portion. The fixed portion of the contact is connected electrically with a conducting circuit pattern portion provided on the main printed circuit board. The movable portion of the conductive contact constitutes an operating part which is moved by the actuator.
In the previously proposed electrical connector as mentioned above, when the flexible printed circuit board is partially inserted into the housing through the opening provided thereon and the actuator is rotated in a predetermined direction, the actuator operates to move the movable portion of each of the conductive contacts to come into press-contact with a corresponding one of the connecting terminals provided on the flexible printed circuit board, as shown in, for example, the Japanese patent application published before examination under publication number 2002-270290 (Publication document 1). Then, when the actuator by which the operating part of each of the conductive contacts is brought into press-contact with the corresponding connecting terminal provided on the flexible printed circuit board is rotated in a direction opposite to the predetermined direction, the movable portion of each of the conductive contacts is allowed by the actuator to move for getting out of press-contact with the corresponding connecting terminal provided on the flexible printed circuit board.
In such an electrical connector as shown in the published document 1, each of the conductive contacts is formed into an H-shaped member. The H-shaped member has a pair of beams coupled with each other through a connecting portion. One of the beams constitutes the fixed portion of the conductive contact and the other of the beams constitutes the movable portion, namely, the operating part of the conductive contact. When the flexible printed circuit board is partially inserted into the housing through the opening provided thereon, a portion of the flexible printed circuit board, on which the connecting terminals are provided, is placed between the fixed and movable portions of each of the conductive contacts. When the actuator is rotated for moving the movable portion of each of the conductive contacts to come into press-contact with the corresponding connecting terminal provided on the flexible printed circuit board, the portion of the flexible printed circuit board, on which the connecting terminals are provided, is held between the fixed portion of each of the conductive contacts and the movable portion of each of the conductive contacts which is brought into press-contact with the corresponding connecting terminal.
Further, there has been another type of the previously proposed electrical connector which is provided with a housing having an opening through which a flexible printed circuit board is partially inserted into the housing, a plurality of conductive contacts arranged along the opening on the housing and an actuator attached rotatably to the housing in almost the same manner as those of the electrical connector shown in the publication document 1, and in which the conductive contacts, each of which is formed into an H-shaped member having fixed and movable portions coupled with each other through a connecting portion, are divided into first and second groups, as shown in, for example, the Japanese patent application published before examination under publication number 2004-342426 (Published document 2).
In the electrical connector as shown in the published document 2, the movable portion of each of the conductive contacts belonging to the first group and the movable portion of each of the conductive contacts belonging to the second group are different in length from each other. When the flexible printed circuit board is partially inserted into the housing through the opening provided thereon and the actuator is rotated for moving the movable portion of each of the conductive contacts belonging to the first and second groups to come into press-contact with the corresponding connecting terminal provided on the flexible printed circuit board, a distance from an end of the connecting terminal which corresponds to the conductive contact belonging to the first group to a portion of that connecting terminal with which the conductive contact belonging to the first group comes into press-contact is different from a distance from an end of the connecting terminal which corresponds to the conductive contact belonging to the second group to a portion of that connecting terminal with which the conductive contact belonging to the second group comes into press-contact. The conductive contacts belonging to the first group and the conductive contacts belonging to the second group are arranged alternately.
In the electrical connector thus proposed previously to be used for mounting the flexible printed circuit board on the main printed circuit board, when the flexible printed circuit board is partially inserted into the housing through the opening provided thereon and the actuator is rotated in the predetermined direction for moving the movable portion of each of the conductive contacts to come into press-contact with the corresponding connecting terminal provided on the flexible printed circuit board, the actuator operates to move the movable portions of the conductive contacts at the same time so that all movable portions of the conductive contacts come simultaneously into press-contact with the connecting terminals provided on the flexible printed circuit board and therefore retroactive force from all movable portions of the conductive contacts acts simultaneously on the actuator.
The amount of the retroactive force from all movable portions of the conductive contacts reaches the maximum value when the movement of the movable portion of each of the conductive contacts is at the maximum. This maximum value of the amount of the retroactive force from all movable portions of the conductive contacts is relatively large because each of the conductive contacts is made of resilient material. In the case where a large number of the conductive contacts are provided in the housing, as disclosed in the publication document 1 or 2, an especially large amount of the retroactive force from all movable portions of the conductive contacts acts on the actuator.
It has been usual that the actuator has a relatively small dimension in a direction perpendicular to a rotating axis extending along the arrangement of the conductive contacts compared with a dimension in the direction of the rotating axis so that the height on the actuator on the main printed circuit board is restrained at the minimum when the actuator is caused to rise from the housing.
Consequently, an operation for rotating the actuator becomes heavy and a relatively large force is necessary for rotating the actuator. This results in a disadvantage that the actuator is inferior in its operational easiness. In addition, it is feared that the actuator which is inferior in its operational easiness is damaged with an excessive force acted on the actuator for rotating the same coercively.